1. Field of the invention
The present invention generally relates to an uninterruptible power supply system composed of an uninterruptible power supply and equipment to be supplied with power such as a computer system, and in particular to test method and system for the uninterruptible power supply.
2. Description of the Related Art
An uninterruptible power supply (UPS) unit has been mandatory equipment if a blackout will cause the loss of crucial data. A UPS unit is equipped with a battery and a sensor for sensing a loss of power. When the sensor detects a loss of power, it immediately switches over to the battery so that continuous power is supplied to a computer system and the user has time to save crucial data and shut off the computer. The battery is usually charged while the computer is switched on.
There has been proposed a power supply system equipped with a backup-battery check circuit in Japanese Patent Unexamined Publication No. 4-147076. More specifically, when powered on, the backup-battery check circuit checks the output voltage of the backup battery in such a state that a battery charger is disconnected from the backup battery. Therefore, a precise and reliable voltage check can be achieved. After the check has been completed, the battery charger starts charging the backup battery and supplying power to a system that is to be backed up.
According to the conventional system, however, since the backup-battery check operation is performed only at power-on, failure of backup battery cannot be checked without an operator.
Further, the backup-battery check circuit is connected to a backup power supply line at a predetermined position and checks whether failure of backup battery occurs. Since the backup-battery check circuit is also connected to the system that is to be backed up, it can check only a part of the backup power supply line. In other words, the backup-battery check circuit cannot check the overall backup power supply line.